Study of the influence of ZrB2 content and thermal shock on the elastic modulus of spark plasma sintered ZrB2-B4C composites using a non-destructive ultrasonic technique

Abstract

Non-destructive ultrasound phase spectroscopy (UPS) was used to study the influence of thermal shock on the longitudinal elastic constant (C11) of ZrB2-B4C composites. C11 of the composites was measured in the as-fabricated condition and after different numbers of thermal shock cycles. The relative change in C11 was used as the thermal shock resistance parameter. Composites with 70 and 50 vol% ZrB2 were subjected to three thermal shock temperature differences (ΔT) of 600 °C, 800 °C, and 1000 °C, respectively. The rate of drop in C11 increased significantly with an increase in ΔT and B4C content. The mechanism of thermal shock damage has been discussed considering the influence of processing-induced thermal residual stresses and the average stress state in both phases during thermal shock. It was shown that the powder particle arrangement plays a major role in the damage mechanism and B4C-B4C particle contacts provide easy paths for crack propagation.